“Practical multiple scattering for rough surfaces”
Conference:
Type(s):
Title:
- Practical multiple scattering for rough surfaces
Session/Category Title: Rendering & reflectance
Presenter(s)/Author(s):
Moderator(s):
Abstract:
Microfacet theory concisely models light transport over rough surfaces. Specular reflection is the result of single mirror reflections on each facet, while exact computation of multiple scattering is either neglected, or modeled using costly importance sampling techniques. Practical but accurate simulation of multiple scattering in microfacet theory thus remains an open challenge. In this work, we revisit the traditional V-groove cavity model and derive an analytical, cost-effective solution for multiple scattering in rough surfaces. Our kaleidoscopic model is made up of both real and virtual V-grooves, and allows us to calculate higher-order scattering in the microfacets in an analytical fashion. We then extend our model to include nonsymmetric grooves, allowing for additional degrees of freedom on the surface geometry, improving multiple reflections at grazing angles with backward compatibility to traditional normal distribution functions. We validate the accuracy of our model against ground-truth Monte Carlo simulations, and demonstrate its flexibility on anisotropic and textured materials. Our model is analytical, does not introduce significant cost and variance, can be seamless integrated in any rendering engine, preserves reciprocity and energy conservation, and is suitable for bidirectional methods.
References:
1. M. Ashikmin, S. Premoze, and P. Shirley. 2000. A Microfacet-based BRDF Generator. In SIGGRAPH. 65–74. Google ScholarDigital Library
2. S.-H. Baek, D. S. Jeon, X. Tong, and M. H. Kim. 2018. Simultaneous Acquisition of Polarimetric SVBRDF and Normals. ACM Trans. Graph. 37, 6 (2018). Google ScholarDigital Library
3. P. Beckmann and A. Spizzichino. 1963. The scattering of electromagnetic waves from rough surfaces. Int Ser. Monographs. Electomagn Waves 4 (1963).Google Scholar
4. C. Bosch, X. Pueyo, S. Merillou, and D. Ghazanfarpour. 2004. A Physically Based Model for Rendering Realistic Scratches. Comput. Graph. Forum 23, 3 (2004), 361–370.Google ScholarCross Ref
5. C. Bourlier and G. Berginc. 2004. Multiple scattering in the high-frequency limit with second-order shadowing function from 2D anisotropic rough dielectric surfaces: I. Theoretical study. Wave. Random Media 14, 3 (2004), 253–276.Google ScholarCross Ref
6. C. Bourlier, G. Berginc, and J. Saillard. 2002. Monostatic and bistatic statistical shadowing functions from a one-dimensional stationary randomly rough surface: II. Multiple scattering. Wave. Random Media 12, 2 (2002), 175–200.Google ScholarCross Ref
7. R. L. Cook and K. E. Torrance. 1982. A Reflectance Model for Computer Graphics. ACM Trans. Graph. 1, 1 (1982), 7–24. Google ScholarDigital Library
8. Z. Dong, B. Walter, S. Marschner, and D. P. Greenberg. 2015. Predicting appearance from measured microgeometry of metal surfaces. ACM Trans. Graph. 35, 1 (2015), 9. Google ScholarDigital Library
9. J. Dupuy, E. Heitz, and E. d’Eon. 2016. Additional Progress Towards the Unification of Microfacet and Microflake Theories. In Proc. Eurograph. Symp. Rendering. 55–63. Google ScholarDigital Library
10. B. W. Hapke. 1963. A theoretical photometric function for the lunar surface. J. Geophy. Re. 68, 15 (1963), 4571–4586.Google ScholarCross Ref
11. E. Heitz. 2014. Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs. J. Comput. Graph. Techn. 3, 2 (2014), 48–107.Google Scholar
12. E. Heitz and E. d’Eon. 2014. Importance Sampling Microfacet-Based BSDFs using the Distribution of Visible Normals. Comput. Graph. Forum 33, 4 (2014), 103–112.Google ScholarDigital Library
13. E. Heitz, J. Hanika, E. d’Eon, and C. Dachsbacher. 2016. Multiple-scattering Microfacet BSDFs with the Smith Model. ACM Trans. Graph. 35, 4 (2016), 58:1–58:14. Google ScholarDigital Library
14. N. Holzschuch and R. Pacanowski. 2017. A two-scale microfacet reflectance model combining reflection and diffraction. ACM Trans. Graph. 36, 4 (2017), 66. Google ScholarDigital Library
15. W. Jakob. 2010. Mitsuba renderer. http://www.mitsuba-renderer.org.Google Scholar
16. W. Jakob, E. d’Eon, O. Jakob, and S. Marschner. 2014. A Comprehensive Framework for Rendering Layered Materials. ACM Trans. Graph. 33, 4 (2014), 118:1–118:14. Google ScholarDigital Library
17. C. Kelemen and L. Szirmay-Kalos. 2001. A Microfacet Based Coupled Specular-Matte BRDF Model with Importance Sampling. In Proc. Eurograph. Short Presentations, Vol. 2. 4.Google Scholar
18. J. J. Koenderink, A. J. Van Doorn, K. J. Dana, and S. Nayar. 1999. Bidirectional reflection distribution function of thoroughly pitted surfaces. Int. J. Comput. Vis. 31, 2–3 (1999), 129–144. Google ScholarDigital Library
19. C. Kulla and A. Conty. 2017. Revisiting Physically Based Shading at Imageworks. In Physically Based Shading in Theory and Practice, SIGGRAPH 2017 Courses.Google Scholar
20. S. Merillou, J.M. Dischler, and D. Ghazanfarpour. 2001. Surface scratches: measuring, modeling and rendering. Vis. Comput. 17, 1 (2001), 30–45.Google ScholarCross Ref
21. G. Nam, J. H. Lee, D. Gutierrez, and M. H. Kim. 2018. Practical SVBRDF Acquisition of 3D Objects with Unstructured Flash Photography. ACM Trans. Graph. 37, 6 (2018). Google ScholarDigital Library
22. G. Nam, J. H. Lee, H. Wu, D. Gutierrez, and M. H. Kim. 2016. Simultaneous Acquisition of Microscale Reflectance and Normals. ACM Trans. Graph. 35, 6 (2016), 185:1–185:11. Google ScholarDigital Library
23. M. Oren and S. K. Nayar. 1994. Generalization of Lambert’s Reflectance Model. In SIGGRAPH. 239–246. Google ScholarDigital Library
24. P. Poulin and A. Fournier. 1990. A Model for Anisotropic Reflection. SIGGRAPH Comput. Graph. 24, 4 (1990), 273–282. Google ScholarDigital Library
25. B. Raymond, G. Guennebaud, and P. Barla. 2016. Multi-scale rendering of scratched materials using a structured SV-BRDF model. ACM Trans. Graph. 35, 4 (2016), 57. Google ScholarDigital Library
26. S. Rusinkiewicz. 1998. A New Change of Variables for Efficient BRDF Representation. In Rendering Techniques ’98 (Proceedings of Eurographics Rendering Workshop ’98), G. Drettakis and N. Max (Eds.). Springer Wien, 11–22.Google ScholarCross Ref
27. D. Saint-Pierre, R. Deeb, D. Muselet, L. Simonot, and M. Hébert. 2018. Light interreflections and shadowing effects in a Lambertian V-cavity under diffuse illumination. J. Electron. Imag. (2018).Google Scholar
28. B. Smith. 1967. Geometrical shadowing of a random rough surface. IEEE Trans. Antennas Propag. 15, 5 (1967), 668–671.Google ScholarCross Ref
29. K. E. Torrance and E. M. Sparrow. 1967. Theory for Off-Specular Reflection From Roughened Surfaces. J. Opt. Soc. Am. 57, 9 (1967), 1105–1114.Google ScholarCross Ref
30. B. Walter, S. R. Marschner, H. Li, and K. E. Torrance. 2007. Microfacet Models for Refraction Through Rough Surfaces. In Proc. Eurograph. Symp. Rendering. 195–206. Google ScholarDigital Library
31. R. B. Zipin. 1966. The apparent thermal radiation properties of an isothermal V-groove with specularly reflecting walls. J. Res. NBS C 70 (1966), 275–280.Google Scholar
